Largest 120/208 volt service

charlie b

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Staff member
Location
Seattle, WA
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Electrical Engineer
I recall being involved in a design that had a 120/208V, 5000 amp main board. It was for a mixed use high rise building. There was an interest in an even higher rating. But there was some issue with the utility company's limits on their metering equipment.
 

infinity

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Staff member
Location
New Jersey
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Journeyman Electrician
Our current project has 4-4000 amp services at 208Y/120 volts. That's the largest I've ever installed at that voltage. If I remember correctly years ago we had a 5000 amp service at 480Y/277 volts.
 

brantmacga

Senior Member
Location
Georgia
Occupation
Electrical contractor
Our current project has 4-4000 amp services at 208Y/120 volts. That's the largest I've ever installed at that voltage. If I remember correctly years ago we had a 5000 amp service at 480Y/277 volts.
I’m curious about this.... what type of facility is it? I’m guessing it had to be more cost effective to purchase the transformers from the utility and have them install.


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mbrooke

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United States
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*
Our current project has 4-4000 amp services at 208Y/120 volts. That's the largest I've ever installed at that voltage. If I remember correctly years ago we had a 5000 amp service at 480Y/277 volts.


What type of facility? How many POCO transformers? How many stories?
 
I’m curious about this.... what type of facility is it? I’m guessing it had to be more cost effective to purchase the transformers from the utility and have them install.


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Me too. Seems like taking service at MV and distributing that around rather than sending that much 208 around from one (or 4) locations would be more efficient.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
I’m curious about this.... what type of facility is it? I’m guessing it had to be more cost effective to purchase the transformers from the utility and have them install.
What type of facility? How many POCO transformers? How many stories?
Apartment complex, two towers, one 26 stories the other 40 stories. About 720 units with a large amenities space. Not sure why they went with a 208Y/120 volt services typically these would be 480Y/277. Could be they didn't want to put in a 480 volt network system which requires space within the building. So we now have about a dozen step-up substations in the service room of the building, some 480 volts some 4160. The 4160 is stepped down to 208Y/120 for apartment power as it goes up the building.
 

brantmacga

Senior Member
Location
Georgia
Occupation
Electrical contractor
Apartment complex, two towers, one 26 stories the other 40 stories. About 720 units with a large amenities space. Not sure why they went with a 208Y/120 volt services typically these would be 480Y/277. Could be they didn't want to put in a 480 volt network system which requires space within the building. So we now have about a dozen step-up substations in the service room of the building, some 480 volts some 4160. The 4160 is stepped down to 208Y/120 for apartment power as it goes up the building.
That sounds like a fun project; I have zero experience with buildings of that size. Is the 480 for HVAC and common area/exterior lighting?
 
Apartment complex, two towers, one 26 stories the other 40 stories. About 720 units with a large amenities space. Not sure why they went with a 208Y/120 volt services typically these would be 480Y/277. Could be they didn't want to put in a 480 volt network system which requires space within the building. So we now have about a dozen step-up substations in the service room of the building, some 480 volts some 4160. The 4160 is stepped down to 208Y/120 for apartment power as it goes up the building.
You got any help on this project or just you? :lol:
 

mbrooke

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Location
United States
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*
Apartment complex, two towers, one 26 stories the other 40 stories. About 720 units with a large amenities space. Not sure why they went with a 208Y/120 volt services typically these would be 480Y/277. Could be they didn't want to put in a 480 volt network system which requires space within the building. So we now have about a dozen step-up substations in the service room of the building, some 480 volts some 4160. The 4160 is stepped down to 208Y/120 for apartment power as it goes up the building.
I might have done it the same way. If 208 makes the bulk of the load it makes sense IMO. Hate to see a 225kva step down on every floor.
 

gar

Senior Member
190911-2216 EDT

Not AC and I never saw it run except in some movies. If memory is correct 240 VDC at about 25,000 A. Maximum distance to any load was probably under 2000 ft. I have no idea of possible short circuit current. There were about 12 of these side by side in the Ford Highland Park Model T plant. I believe installed before 1915. The one remaining unit is in the Henry Ford Museum. It is a huge machine. The flywheel is possibly about 20 ft in diameter.

Movie of the generator1919 https://www.youtube.com/watch?v=JIVEKxKDexU
the movie that follows this one is 1937 or 8 of the Rouge plant. This is only about 6 years after two of my classmates fathers worked in a very small group that developed the V8. This movie is very much like movies that were shown at the Ford Rotunda in days past.

There were many times I climbed around that hugh generator and looked at its construction.

.
 
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infinity

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Staff member
Location
New Jersey
Occupation
Journeyman Electrician
That sounds like a fun project; I have zero experience with buildings of that size. Is the 480 for HVAC and common area/exterior lighting?
Yes the 480Y/277 is for the chillers, HVAC, elevators, fans, pumps, etc.

I might have done it the same way. If 208 makes the bulk of the load it makes sense IMO. Hate to see a 225kva step down on every floor.
IMO the flaw is that instead of that (208 volt vertical risers) we have 4160 step-up and 4160-208Y/120 step down transformers for the apartment power anyway. All of the 480 is derived from huge transformers as well. It is nice to run a single 2.5" riser the height of the building and end up with 1000 amps at 208Y/120 on the other end. :thumbsup:
 

Tony S

Senior Member
Not one of my jobs, I got an email from a friend asking if I knew where he could get an 8000A disconnect from. He was in Russia on a job that was to be done to BS7671 but using 208/120V ? ? ? ?

Don’t ask me why, because I don’t know.

6300A was the best I could come up with.
My first answer was “why don’t you use 3.3kV?”
“They want the whole site has to be 208/120V.”
“Telemecanique can gang disconnects.”

What size the cables did they used? I dread to think.
 
Yes the 480Y/277 is for the chillers, HVAC, elevators, fans, pumps, etc.



IMO the flaw is that instead of that (208 volt vertical risers) we have 4160 step-up and 4160-208Y/120 step down transformers for the apartment power anyway. All of the 480 is derived from huge transformers as well. It is nice to run a single 2.5" riser the height of the building and end up with 1000 amps at 208Y/120 on the other end. :thumbsup:
How is metering handled? Is electric included for tenants?
 

mayanees

Senior Member
Location
Westminster, MD
208 Volt, 3 phase, 4000-amp at a hospital in Brooklyn, NY. And it was probably 50+ years old. The reported fault current was 200kA. There were five 1000 kVA transformers network-connected on the other side of the wall in the basement of the facility.

I was doing data collection for an arc flash study and couldn't 't find the current-limiting fuses that were shown on the drawings. So I took 40 nuts off the cover off a 3' by 4' protruding enclosure. The cover was held by 4 captive studs. When I popped the cover off to inspect it, I found the 4000-amp, 208 Volt busbar was about 3/4' from the face of the cover. It scared the bejeezus out of me, but it made sense. There wasn't the need for much clearance because it was just 208 Volts.
 

mbrooke

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United States
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*
208 Volt, 3 phase, 4000-amp at a hospital in Brooklyn, NY. And it was probably 50+ years old. The reported fault current was 200kA. There were five 1000 kVA transformers network-connected on the other side of the wall in the basement of the facility.

I was doing data collection for an arc flash study and couldn't 't find the current-limiting fuses that were shown on the drawings. So I took 40 nuts off the cover off a 3' by 4' protruding enclosure. The cover was held by 4 captive studs. When I popped the cover off to inspect it, I found the 4000-amp, 208 Volt busbar was about 3/4' from the face of the cover. It scared the bejeezus out of me, but it made sense. There wasn't the need for much clearance because it was just 208 Volts.
How did you end up dealing with 200ka fault current?

What you describe is typical, not the exception in NY.
 
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